Rajoy replied he accepted to speak to Cameron upon London's request and that the security measures in place at the Gibraltar border are needed to "prevent illegal trafficking" and perfectly fulfil international standards and agreements.

The Moncloa Palace also blamed Gibraltar for triggering the diplomatic row, saying the dumping of 70 concrete blocks in the bay was an "unacceptable unilateral act."

"[The dumping] has led to considerable discontent and significant concerns in Spain following the harm caused to the environment and fishing activity," Rajoy said.

Gibraltar's chief minister, Fabian Picardo, this week accused Madrid of "sabre-rattling" and behaving like North Korea.

The Prime Ministers' phone call came after the UK ambassador to Madrid, Giles Paxman, lodged a formal protest with Spanish authorities over the increased border checks Britain says are disproportionate.

Madrid has also threatened to levy a €50 (£43) charge on vehicles crossing the border and to close airspace.